This invention relates to inhibitors of beta amyloid production, which have utility in the treatment of Alzheimer""s disease.
Alzheimer""s Disease (AD) is the most common form of dementia (loss of memory) in the elderly. The main pathological lesions of AD found in the brain consist of extracellular deposits of beta amyloid protein in the form of plaques and angiopathy and intracellular neurofibrillary tangles of aggregated hyperphosphorylated tau protein. Recent evidence has revealed that elevated beta amyloid levels in brain not only precede tau pathology but also correlate with cognitive decline. Further suggesting a causative role for beta amyloid in AD, recent studies have shown that aggregated beta amyloid is toxic to neurons in cell culture.
Beta amyloid protein is composed mainly of 39-42 amino acid peptides and is produced from a larger precursor protein called amyloid precursor protein (APP) by the sequential action of the proteases beta and gamma secretase. Although rare, cases of early onset AD have been attributed to genetic mutations in APP that lead to an overproduction of either total beta amyloid protein or its more aggregation-prone 42 amino acid isoform. Furthermore, people with Down""s Syndrome possess an extra chromosome that contains the gene that encodes APP and thus have elevated beta amyloid levels and invariably develop AD later in life.
There continues to be an unmet need for compositions useful in inhibiting beta amyloid production and in the treatment of the effects of Alzheimer""s Disease (AD).
The present invention provides heterocyclic sulfonamide derivatives of 2-amino-1-alcohols and related homologs that have been found to specifically inhibit the production of beta amyloid protein from APP and to be capable of passing through the blood-brain barrier. These compounds are useful for the treatment of conditions in which beta amyloid levels are elevated (e.g., AD, Down""s Syndrome). Systemic administration of these compounds to subjects at risk of, or suffering from, these diseases lowers beta amyloid protein levels with subsequent reduction in the toxic beta amyloid aggregates in the brains of these patients.
In one aspect, the present invention provides a compound of Formula (I), as defined herein, pharmaceutically acceptable salts, hydrates, or prodrugs thereof. In one embodiment, the compounds of Formula (I) are thiophenesulfonamides. In another embodiment, the compounds of Formula (I) are furansulfonamides. Among the particularly desirable compounds are those having a halogen in the 5-position of the heterocycle (e.g., 5-halo thiophenesulfonamides) and xcex2-branches in the side chain of the primary alcohol.
In another aspect, the invention provides a pharmaceutical composition containing one or more compounds of Formula (I) and a physiologically compatible carrier.
In yet another aspect, the invention provides a method of inhibiting beta amyloid production in a subject by delivering a compound of Formula (I).
In still another aspect, the invention provides a method of treating Alzheimer""s Disease (AD) in a subject by administering a compound of Formula (I) to the subject in an amount sufficient to alleviate the symptoms or progress of AD.
These and other aspects of the invention will be apparent to one of skill in the art upon reading of the following detailed description of the invention.
The invention consists of compounds of Formula (I), their pharmaceutical formulations, and their use in modulating beta amyloid production in subjects at risk for, or suffering from, AD or other diseases resulting from elevated levels of beta amyloid protein in the brain. The compounds of Formula (I) include pharmaceutically acceptable salts and/or hydrates or prodrugs thereof, wherein: 
R1 and R2 are independently selected from the group consisting of hydrogen, alkyl, substituted alkyl, CF3, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, cycloalkyl, substituted cycloalkyl, phenyl, substituted phenyl, and (CH2)n(1,3)dioxane, where n is 2 to 5;
R3 is selected from the group consisting of hydrogen, alkyl, and substituted alkyl;
R4 is selected from the group consisting of hydrogen, alkyl, substituted alkyl, alkylcycloalkyl, substituted alkylcycloalkyl, phenyl(substituted)alkyl, alkylOH, substituted alkylOH, alkylOBn, substituted alkylOBn, alkylpyridyl, substituted alkylpyridyl, alkylfuranyl, substituted alkylfuranyl, CH(OH)phenyl, CH(OH)substituted phenyl, alkenyl, substituted alkenyl, cycloalkyl, substituted cycloalkyl, N-substituted-piperidinyl, piperidinyl, substituted piperidinyl, tetrahydrothiopyran, substituted tetrahydrothiopyran, 2-indane, substituted 2-indane, phenyl, substituted phenyl, alkylNHR7, and substituted alkylNHR7;
with the proviso that R3 and R4 are not both hydrogen;
R7 is alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, benzyl, substituted benzyl, alkylOH, substituted alkylOH, alkylSR8, or substituted alkylSR8;
R8 is alkyl, substituted alkyl, benzyl, or substituted benzyl;
or R3 and R4 may be joined to form a ring;
R5 is selected from the group consisting of hydrogen, lower alkyl, substituted lower alkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, CH2cycloalkyl, substituted CH2cycloalkyl, benzyl, substituted benzyl, and CH2CH2QR9;
Q is O, NH or S;
R9 is lower alkyl, substituted lower alkyl, phenyl, or substituted phenyl;
R6 is selected from the group consisting of hydrogen, halogen and CF3;
T is selected from the group consisting of 
W, Y and Z are independently selected from the group consisting of C, CR10 and N;
R10 is selected from the group consisting of hydrogen and halogen, with the proviso that at least one of W, Y and Z must be C;
X is selected from the group consisting of O, S, SO2, and NR11;
R11 is selected from the group consisting of hydrogen, lower alkyl, substituted lower alkyl, benzyl, substituted benzyl, phenyl, and substituted phenyl;
provided that when the compound contains one or more chiral centers, at least one of the chiral centers must be of S-stereochemistry.
The point of attachment of the Wxe2x80x94Xxe2x80x94Yxe2x80x94Zxe2x80x94C heterocyclic ring to the SO2 group is not a limitation of the present invention. However, in one preferred embodiment, the ring is attached to the SO2 group through a carbon-atom. However, the ring may be attached through O, S, or N heteroatoms.
The compounds of the invention may contain one or more asymmetric carbon atoms and some of the compounds may contain one or more asymmetric (chiral) centers and may, thus give rise to optical isomers and diastereomers. While shown without respect to stereochemistry in Formula (I), when the compounds of Formula (I) contain one or more chiral centers, at least one of the chiral centers is of S-stereochemistry. Most preferably, the carbon atom to which N, T, R3 and R4 are attached is of S-stereochemistry. Thus, the invention includes such optical isomers and disastereomers; as well as the racemic and resolved, enantiomerically pure stereoisomers; as well as other mixtures of the R and S stereoisomers, and pharmaceutically acceptable salts, hydrates, and prodrugs thereof.
The term xe2x80x9calkylxe2x80x9d is used herein to refer to both straight- and branched-chain saturated aliphatic hydrocarbon groups having one to ten carbon atoms, preferably one to eight carbon atoms and, most preferably, one to six carbon atoms; as used herein, the term xe2x80x9clower alkylxe2x80x9d refers to straight- and branched-chain saturated aliphatic hydrocarbon groups having one to six carbon atoms; xe2x80x9calkenylxe2x80x9d is intended to include both straight- and branched-chain alkyl group with at least one carbonxe2x80x94carbon double bond and two to eight carbon atoms, preferably two to six carbon atoms; xe2x80x9calkynylxe2x80x9d group is intended to cover both straight- and branched-chain alkyl groups with at least one carbonxe2x80x94carbon triple bond and two to eight carbon atoms, preferably two to six carbon atoms.
The terms xe2x80x9csubstituted alkylxe2x80x9d, xe2x80x9csubstituted alkenylxe2x80x9d, and xe2x80x9csubstituted alkynylxe2x80x9d refer to alkyl, alkenyl, and alkynyl as just described having from one to three substituents selected from the group including halogen, CN, OH, NO2, amino, aryl, heterocyclic, substituted aryl, substituted heterocyclic, alkoxy, substituted alkoxy, aryloxy, substituted alkyloxy, alkylcarbonyl, alkylcarboxy, alkylamino, arylthio. These substituents may be attached to any carbon of an alkyl, alkenyl, or alkynyl group provided that the attachment constitutes a stable chemical moiety.
The term xe2x80x9carylxe2x80x9d is used herein to refer to a carbocyclic aromatic system, which may be a single ring, or multiple aromatic rings fused or linked together as such that at least one part of the fused or linked rings forms the conjugated aromatic system. The aryl groups include, but are not limited to, phenyl, naphthyl, biphenyl, anthryl, tetrahydronaphthyl, phenanthryl, and indane.
The term xe2x80x9csubstituted arylxe2x80x9d refers to aryl as just defined having one to four substituents from the group including halogen, CN, OH, NO2, amino, alkyl, cycloalkyl, alkenyl, alkynyl, alkoxy, aryloxy, substituted alkyloxy, alkylcarbonyl, alkylcarboxy, alkylamino, and arylthio.
The term xe2x80x9csubstituted benzylxe2x80x9d refers to a benzyl group, having substituted on the benzene ring, one to five substituents from the group including halogen, CN, OH, NO2, amino, alkyl, cycloalkyl, alkenyl, alkynyl, alkoxy, aryloxy, substituted alkyloxy, alkylcarbonyl, alkylcarboxy, alkylamino, and arylthio.
The term xe2x80x9cheterocyclicxe2x80x9d is used herein to describe a stable 4- to 7-membered monocyclic or a stable multicyclic heterocyclic ring which is saturated, partially unsaturated, or unsaturated, and which consists of carbon atoms and from one to four heteroatoms selected from the group including N, O, and S atoms. The N and S atoms may be oxidized. The heterocyclic ring also includes any multicyclic ring in which any of above defined heterocyclic rings is fused to an aryl ring. The heterocyclic ring may be attached at any heteroatom or carbon atom provided the resultant structure is chemically stable. Such heterocyclic groups include, for example, tetrahydrofuran, piperidinyl, piperazinyl, 2-oxopiperidinyl, azepinyl, pyrrolidinyl, imidazolyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, oxazolyl, isoxazolyl, morpholinyl, indolyl, quinolinyl, thienyl, furyl, benzofuranyl, benzothienyl, thiamorpholinyl, thiamorpholinyl sulfoxide, isoquinolinyl, and tetrahydrothiopyran.
The term xe2x80x9csubstituted heterocyclicxe2x80x9d is used herein to describe the heterocyclic just defined having one to four substituents selected from the group which includes halogen, CN, OH, NO2, amino, alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, alkenyl, substituted alkenyl, alkynyl, substituted alkynyl, alkoxy, substituted alkoxy, aryloxy, substituted aryloxy, alkyloxy, substituted alkyloxy, alkylcarbonyl, substituted alkylcarbonyl, alkylcarboxy, substituted alkylcarboxy, alkylamino, substituted alkylamino, arylthio, or substituted arylthio.
The term xe2x80x9csubstituted cycloalkylxe2x80x9d is used herein to describe a carbon-based ring having more than 3 carbon-atoms which forms a stable ring and having from one to five substituents selected from the group consisting of halogen, CN, OH, NO2, amino, alkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl, alkoxy, aryloxy, substituted alkyloxy, alkylcarbonyl, alkylcarboxy, alkylamino, substituted alkylamino, arylthio, heterocyclic, substituted heterocyclic, aminoalkyl, and substituted aminoalkyl.
Where the terms xe2x80x9csubstituted alkylcycloalkylxe2x80x9d, xe2x80x9csubstituted alkylOBnxe2x80x9d, xe2x80x9csubstituted alkylpyridylxe2x80x9d, xe2x80x9csubstituted alkylfuranylxe2x80x9d, xe2x80x9csubstituted alkyl NHR7xe2x80x9d, xe2x80x9csubstituted alkylOHxe2x80x9d, and xe2x80x9csubstituted alkylSR8xe2x80x9d are recited, the substitution may occur at the alkyl group or on the corresponding base compound.
As used in the definition of the R4 group, an N-substituted piperidinyl group may be defined as are the substituted heterocyclic groups. Among particularly desirable substituents are N-alkyl-, N-aryl-, N-acyl-, and N-sulfonyl piperidinyl groups. One particularly suitable N-acyl-piperidinyl group is N-t-butyloxycarbonyl (BOC)-piperidine. However, other suitable substituents can be readily identified by one of skill in the art.
The term xe2x80x9calkoxyxe2x80x9d is used herein to refer to the OR group, where R is alkyl or substituted alkyl. The term xe2x80x9caryloxyxe2x80x9d is used herein to refer to the OR group, where R is aryl or substituted aryl. The term xe2x80x9calkylcarbonylxe2x80x9d is used herein to refer to the RCO group, where R is alkyl or substituted alkyl. The term xe2x80x9calkylcarboxyxe2x80x9d is used herein to refer to the COOR group, where R is alkyl or substituted alkyl. The term xe2x80x9caminoallkylxe2x80x9d refers to both secondary and tertiary amines wherein the alkyl or substituted alkyl groups, containing one to eight carbon atoms, which may be either same or different and the point of attachment is on the nitrogen atom.
The term xe2x80x9chalogenxe2x80x9d refers to Cl, Br, F, or I.
The term xe2x80x9cringxe2x80x9d structure, e.g., when R3 and R4 may form a ring structure, includes a monocyclic structure, a bridged cyclo structure, and fused cyclo structures, unless the type of ring structure is otherwise specified.
The compounds of the present invention can be used in the form of salts derived from pharmaceutically or physiologically acceptable acids or bases. These salts include, but are not limited to, the following salts with organic and inorganic acids such as acetic, lactic, citric, tartaric, succinic, fumaric, maleic, malonic, mandelic, mallic, hydrochloric, hydrobromic, phosphoric, nitric, sulfuric, methanesulfonic, toluenesulfonic and similarly known acceptable acids, and mixtures thereof. Other salts include salts with alkali metals or alkaline earth metals, such as sodium (e.g., sodium hydroxide), potassium (e.g., potassium hydroxide), calcium or magnesium.
These salts, as well as other compounds of the invention may be in the form of esters, carbamates and other conventional xe2x80x9cpro-drugxe2x80x9d forms, which, when administered in such form, convert to the active moiety in vivo. In a currently preferred embodiment, the prodrugs are esters. See, e.g., B. Testa and J. Caldwell, xe2x80x9cProdrugs Revisited: The xe2x80x9cAd Hocxe2x80x9d Approach as a Complement to Ligand Designxe2x80x9d, Medicinal Research Reviews, 16(3):233-241, ed., John Wiley and Sons (1996).
In one particularly desirable embodiment, the compounds of Formula (I) are thiophenesulfonamides, and more desirably, 5-halo thiophenesulfonamides, and most desirably, 5-halo thiophene sulfonamides with xcex2-branches in the side chain of a primary alcohol. Thus, with respect to Formula (I), the compound of the invention desirably has a structure in which X is S, W is C (or CR10), Y is C (or CR10) and Z is C (or CR10), and the sulfonamide is attached to C2 of the thiophene ring. More desirably, X is S, W is C (or CR10), Y is C (or CR10), Z is C (or CR10) and R6 is a halogen. Most desirably, X is S, X is C, W is C, Y is C, Z is C, R6 is a halogen, and T is C(OH)R1R2, where R1 and R2 are hydrogen, R3 is H R4 is a lower alkyl of S-stereochemistry, and R5 is II. In preliminary screening assays in vitro and in vivo, compounds of these structures have been found to have unexpectedly good beta-amyloid inhibitory activity, and in many cases, better activity than compounds of Formula (I) having other heterocycles (e.g., furans, where X is O). However, other such compounds of Formula (I) are also useful for the purposes described herein.
For example, in another embodiment, the compounds of Formula (I) are furansulfonamides, in which X is O, W is C, Y is C, and Z is C. In one particularly desirable embodiment, the furansulfonamides of Formula (I) are further characterized by xcex2-branches in the side chain of a primary alcohol. Thus, with respect to Formula (I), in these compounds T is C(OH)R1R2, in which R1 and R2 are hydrogen, R3 is H, R4 is a lower alkyl of S-stereochemistry, R5 is H and R6 is halogen.
In still another embodiment, the compounds of Formula (I) are characterized by being sulfonamides of Formula (I), which have xcex2-branches in the side chain of the primary alcohol group. Thus, with respect to Formula (I), in these compounds T is C(OH)R1R2, R1 and R2 are hydrogen, R3 is H, R4 is a lower alkyl of S-stereochemistry, and R5 is II.
These and the other compounds of the invention can be prepared following the Schemes illustrated below.
The compounds of the present invention can be prepared in a number of ways well known to one skilled in the art of organic synthesis. The compounds of the present invention can be prepared using the methods described below, together with synthetic methods known in the synthetic organic arts or variations of these methods by one skilled in the art. (See, generally, Comprehensive Organic Synthesis, xe2x80x9cSelectivity, Strategy and Efficiency in Modern Organic Chemistryxe2x80x9d, ed., I. Fleming, Pergamon Press, New York (1991); Comprehensive Organic Chemistry, xe2x80x9cThe Synthesis and Reactions of Organic Compoundsxe2x80x9d, ed. J. F. Stoddard, Pergamon Press, New York (1979)). Preferred methods include, but are not limited to, those outlined below.
A first method of preparation consists of reaction of a 2-aminoalcohol II with the appropriate sulfonyl halide in the presence of a base such as triethylamine (TEA) and in a suitable solvent to afford compounds of Formula III. For compounds where R2 and R1 are hydrogen, oxidation of the N-sulfonyl primary alcohol with pyridinium chlorochromate (PCC) or under Swern conditions then affords the corresponding aldehyde IV which can be reacted with Grignard reagents (RMgX, where R is an 
organic radical and X is a halogen) to afford the secondary alcohols V as a mixture of diastereomers which can be separated by high performance liquid chromatography (HPLC) (Scheme 1).
A second method of preparation involves reaction of an xcex1-amino acid or ester IX with the appropriate sulfonyl halide in the presence of a base such as triethylamine and in a suitable solvent to afford compounds of Formula X (Scheme 2). The intermediate N-sulfonyl acid X (Rx=H) can be converted to the corresponding primary alcohol VIII (R1=R2=H) utilizing standard methodology such as LiAlH4, B2H6 or cyanuric chloride/NaBH4. The intermediate N-sulfonyl ester X (Rx=alkyl, Bn) can also be reduced to the corresponding primary alcohol VIII (R1=R2=H) utilizing standard methodology such as LiAlH4. Alternatively, the intermediate N-sulfonyl ester X (Rx=alkyl, Bn) can be converted to the aldehyde IV with DiBAL. Finally, the intermediate N-sulfonyl ester X (Rx=alkyl, Bn) can be reacted with 2 equivalents of Grignard reagent to afford the tertiary alcohols III with R1=R2. Alternatively, for tertiary alcohols III with R1 not equal to R2, the corresponding Weinreb amide (see Scheme 10) of the N-sulfonyl acid can be prepared and 
subsequently reacted with R1MgX and R2MgX. For compounds of formula X (Rx=H) that have an asymmetric center at the xcex1-amino acid carbon, the pure enantiomers can be obtained by standard resolution procedures employing recrystallization of salts formed with various chiral bases.
In a variation of the second method to prepare the primary alcohols, an xcex1-amino acid or ester (or N-protected derivative thereof) VI is first converted to the corresponding primary 2-aminoalcohol VII (using the methodology outlined in the previous paragraph), which is subsequently, after deprotection (if necessary), reacted with the appropriate sulfonyl halide (Scheme 3) to afford compounds of Formula VIII. For preparation of compounds derived from unnatural xcex1-amino acids containing beta branching in the amino acid side chain, a method of preparation based on the work of Hruby (Tet. Lett. 38: 5135-5138 (1997)) is outlined in Scheme 4. This route entails formation of the xcex1,xcex2-unsaturated amide XII of the Evans chiral auxiliary from an xcex1, xcex2-unsaturated acid XI, followed by conjugate addition of an organocuprate, trapping of the resulting enolate anion XIII with NBS, displacement of the bromide XIV with azide anion (provided by tetramethylguanidinium azide (TMGA)) to afford 
XV, followed by reduction to the 2-amino alcohol and subsequent sulfonylation to afford the target compound XVI. In Schemes 1 through 4, R5 is H. 
For the preparation of N-alkylated sulfonamides VIII (R5=alkyl etc.), the sulfonamide ester XVII can be N-alkylated by either treatment with a suitable base such as potassium carbonate followed by the alkylating agent R5X or by employing Mitsunobu conditions (R5OH/DEAD, TPP). LiBH4 reduction of the N-alkylated sulfonamide ester affords the N-alkylated sulfonamide in the primary alcohol series VIII (Scheme 5). These primary alcohols VIII can be converted to the secondary alcohols V or aldehyde IV series by chemistry that has been outlined above. Alternatively, the N-alkylated sulfonamide esters, or their corresponding Weinreb amides, can be treated with Grignard reagents to afford the N-alkylated tertiary alcohols III. 
When the heterocycle attached to the sulfonamide in the above alcohols is thiophene, the corresponding sulfone derivative XIX may be obtained by oxidation of the thiophene compound XVIII with MCPBA (Scheme 6). 
An alternate preparation of sulfonamides derived from unnatural 2-aminoalcohols utilizes the Bucherer modification of the Strecker xcex1-amino acid synthesis (Scheme 7). In this route, an aldehyde XX is reacted with cyanide anion and ammonium carbonate to afford the hydantoin XXI, which is hydrolyzed to the xcex1-amino acid XXII. This compound is then reduced to XXIII and sulfonylated to afford the desired compounds of Formula XXIV. 
For sulfonamides derived from 2-aminoalcohols containing an N or O heteroatom in the side chain, a route has been devised starting from D-serine (Scheme 8). In this route, D-serine XXV is first sulfonylated to XXVI and subsequently converted to the ketone XXVII, which is reductively aminated to the target compounds of Formula XXVIII, 
For sulfonamides derived from 2-aminoalcohols in the secondary alcohol series with R1=H and R2=CF3 (compound XXIX), a method of preparation has been devised that is outlined in Scheme 9 starting from the aldehyde IV (prepared as in Scheme 1). 
As has been mentioned in the section concerning Scheme 1, the preparation of sulfonamides derived from 2-aminoalcohols in the secondary alcohol series V results in the formation of a diastereomeric mixture. An alternate method of preparation of these compounds that results in the production of a pure diastereomer is outlined in Scheme 10 for compounds derived from L-isoleucine. This method, which utilizes chemistry previously employed by Roux (Tetrahedron 50: 5345-5360 (1994)), consists of addition of Grignard reagents to the Weinreb amide XXX (derived from the requisite xcex1-amino acid) followed by stereospecific reduction of the ketone XXXI to afford a single diastereomeric N-protected 2-amino alcohol XXXII. Deprotection of this compound followed by reaction with sulfonyl chlorides affords the pure diastereomeric sulfonamide secondary alcohols of Formula XXXIII. 
When the heterocycle attached to the sulfonamide in the above alcohols is thiophene, the corresponding 5-iodo and 5-fluoro-thiophene derivatives may be obtained by conversation of the 5-bromo-thiophene derivative XXXIV (obtained as in Scheme 1) to a 5-trialkyltin-thiophene intermediate XXXV which can be converted to either the 5-iodo-thiophene (XXXVII) by treatment with sodium iodide and chloramine T or the 5-fluoro-thiophene analog (XXXVI) by treatment with SELECTFLUOR(trademark) (Aldrich Chemical Co) (Scheme 11). 
Sulfonamides derived from cyclohexylglycinol substituted by alkoxy and amino groups at the 4 position of the cyclohexane ring can be prepared according to the methods described herein (Scheme 12). This route entails initial hydrogenation of 4-L-hydroxyphenylglycine XXXVIII, followed by sulfonylation, reduction of the carboxylic acid with diborane and formation of the N,O-acetonide XXXIX. The 4-hydroxy acetonide XXXIX is then O-alkylated using sodium hydride and an alkylating agent such as an alkyl or benzyl bromide. This is followed by removal of the protecting group by treatment with aqueous acid to afford the 4-ether derivatives of Formula XXXX. Alternatively, the 4-hydroxy acetonide XXXIX can be oxidized to the 4-ketone which can be reductively aminated and deprotected to afford the corresponding 4-amino analogs of Formula XXXXI. 
Another method of preparing chirally pure N-sulfonyl 2-amino alcohols derived from xcex1-amino acids is outlined in Scheme 13. This method involves construction of an Evans oxazolidone chiral auxiliary XXXXIII from XXXXII, which is then converted to the corresponding enolate and electrophilically aminated with trisyl azide to afford the key intermediate XXXXIV (J. Am. Chem. Soc. 109: 6881-6883 (1987)). The azide intermediate XXXXIV is then hydrolyzed to the xcex1-azido acid XXXXV and reduced to the chirally pure xcex1-amino acid XXXXVI which can be converted to the corresponding N-sulfonyl 2-amino alcohols by methods previously described above (e.g. Scheme 2). 
Finally, chirally pure xcex1-amino acids XXXXVI, one of the possible synthetic precursors of chiral N-sulfonyl 2-amino alcohols as mentioned above, can also be prepared utilizing an asymmetric variant of the Strecker xcex1-amino acid synthesis as outlined in Scheme 14 (J. Org. Chem. 54:1055-1062 (1989)). 
Oximes XXXXXIV can be derived from the corresponding aldehydes IV by standard methodology as depicted in Scheme 15. 
Compounds of Formula (I) are inhibitors of beta amyloid production. In preliminary studies using protease specific assays, exemplary compounds of Formula (I) have been shown to exhibit specific inhibition with respect to protease activity. Thus, the compounds of the present invention are useful for treatment and prevention of a variety of conditions in which modulation of beta amyloid levels provides a therapeutic benefit. Such conditions include, e.g., amyloid angiopathy, cerebral amyloid angiopathy, systemic amyloidosis, Alzheimer""s Disease (AD), hereditary cerebral hemorrhage with amyloidosis of the Dutch type, inclusion body myositis, Down""s syndrome, among others.
In addition, the compounds of Formula (I) may be utilized in generating reagents useful in diagnosis of conditions associated with abnormal levels of beta amyloid. For example, the compounds of Formula (I) may be used to generate antibodies, which would be useful in a variety of diagnostic assays. Methods for generating monoclonal, polyclonal, recombinant, and synthetic antibodies or fragments thereof, are well known to those of skill in the art. (See, e.g., E. Mark and Padlin, xe2x80x9cHumanization of Monoclonal Antibodiesxe2x80x9d, Chapter 4, The Handbook of Experimental Pharmacology, Vol. 113, The Pharmacology of Monoclonal Antibodies, Springer-Verlag (June, 1994); Kohler and Milstein and the many known modifications thereof; PCT Patent Application No. PCT/GB85/00392; British Patent Application Publication No. GB2188638A; Amit et al., Science, 233:747-753 (1986); Queen et al., Proc. Nat""l. Acad. Sci. USA, 86:10029-10033 (1989); International Patent Publication No. WO90/07861; and Riechmann et al., Nature, 332:323-327 (1988); Huse et al, Science, 246:1275-1281 (1988)). Alternatively, the compounds of Formula (1) may themselves be used in such diagnostic assays. Regardless of the reagent selected (e.g., antibody or compound of Formula (I)), suitable diagnostic formats including, e.g., radioimmunoassays and enzyme-linked immunosorbent assays (ELISAs), are well known to those of skill in the art and are not a limitation on this embodiment of the invention.
The beta amyloid inhibitory activity of many of the compounds of the present invention has been determined using the Repressor Release Assay (RRA). See, Table 23 below. A compound is considered active in RRA if it leads to at least a 1.5 fold increase in luciferase activity at 20 xcexcM and is non-toxic.
Additionally, cellular, cell-free and in vivo screening methods to detect inhibitors of beta amyloid production are known in the art. Such assays may include radioimmunoassays and enzyme-linked immunosorbent assay (ELISA), among others. See, e.g., P. D. Mehta, et al., Techniques in Diagnostic Pathology, vol. 2, eds., Bullock et al, Academic Press, Boston, pages 99-112 (1991), International Patent Publication No. WO 98/22493, European Patent No. 0652009, U.S. Pat. No. 5,703,129 and U.S. Pat. No. 5,593,846. Selection of an appropriate in vitro or in vivo screening assay is not a limitation of the present invention.
The compounds of this invention may be administered to a subject by any desirable route, taking into consideration the specific condition for which it has been selected. By subject is meant any suitable mammal, including humans, domestic animals (e.g., canines and felines), and livestock, which have been recognized as having or at risk of having one or more of the conditions for which modulation of beta amyloid levels is desirable. Thus, the compounds of the invention are useful for treatment and/or prevention of a number of human and veterinary conditions. As used herein, xe2x80x9cpreventionxe2x80x9d encompasses prevention of symptoms in a subject who has been identified as at risk for the condition, but has not yet been diagnosed with the same and/or who has not yet presented any symptoms thereof.
These compounds may be delivered or administered by any suitable route of delivery, e.g., oral, intravenous, subcutaneous, intramuscular, sublingual, intracranial, epidural, intratracheal, rectal, vaginal, among others. Most desirably, the compounds are delivered orally or by a suitable parenteral route. The compounds may be formulated in combination with conventional pharmaceutical carriers that are physiologically compatible. Optionally, one or more of the compounds of the invention may be mixed with other active agents.
Suitable physiologically compatible carriers may be readily selected by one of skill in the art. For example, suitable solid carriers include, among others, one or more substances which may also act as lubricants, solubilizers, suspending agents, fillers, glidants, compression aids, binders or tablet-disintegrating agents or an encapsulating material. In powders, the carrier is a finely divided solid, which is in admixture with the finely divided active ingredient. In tablets, the active ingredient is mixed with a carrier having the necessary compression properties in suitable proportions and compacted in the shape and size desired. The powders and tablets preferably contain up to 99% of the active ingredient. Suitable solid carriers include, for example, starch, sugars (including, e.g., lactose and sucrose), dicalcium phosphate, cellulose (including, e.g., microcrystalline cellulose, methyl cellulose, sodium caroboxymethyl cellulose), and kaolin.
Liquid carriers may be used in preparing solutions, suspensions, emulsions, syrups and elixirs. The active ingredient of this invention can be dissolved or suspended in a pharmaceutically acceptable liquid carrier such as water, an organic solvent, a mixture of both or pharmaceutically acceptable oils or fat. The liquid carrier can contain other suitable pharmaceutical additives such as solubilizers, emulsifiers, buffers, suspending agents, thickening agents, viscosity regulators, stabilizers or osmo-regulators. Suitable examples of liquid carriers for oral and parenteral administration include water (particularly containing additives as above e.g. cellulose derivatives, preferably sodium carboxymethyl cellulose solution), alcohols (including monohydric alcohols and polyhydric alcohols, e.g., glycols) and their derivatives, and oils (e.g., fractionated coconut oil, arachis oil, corn oil, peanut oil, and sesame oil). For parenteral administration the carrier can also be an oily ester such as ethyl oleate and isopropyl myristate. Sterile liquid carriers are used in sterile liquid form compositions for parenteral administration.
Optionally, additives customarily employed in the preparation of pharmaceutical compositions may be included in the compositions of the invention. Such components include, e.g., sweeteners or other flavoring agents, coloring agents, preservatives, and antioxidants, e.g., vitamin E, ascorbic acid, BHT and BHA.
Liquid pharmaceutical compositions that are sterile solutions or suspensions can be utilized by, for example, intramuscular, intraperitoneal or subcutaneous injection. Sterile solutions can also be administered intravenously. Oral administration may be either liquid or solid composition form.
Preferably the pharmaceutical composition is in unit dosage form, e.g. as tablets or capsules. In such form, the composition is sub-divided in unit dose containing appropriate quantities of the active ingredient; the unit dosage forms can be packaged compositions, for example packeted powders, vials, ampoules, prefilled syringes or sachets containing liquids. The unit dosage form can be, for example, a capsule or tablet itself, or it can be the appropriate number of any such compositions in package form.
As described herein, a therapeutically or prophylactically useful amount of a compound of the invention is that amount of a compound which alleviates the symptoms of the disease, e.g., AD, or which prevents the onset of symptoms, or the onset of more severe symptoms. Generally, an individual dose (i.e., per unit, e.g., tablet) of a compound of the invention may be in the range from about 1 xcexcg/kg to about 10 g/kg, more preferably 10 mg/kg to about 5 g/kg, and most preferably about 1 mg/kg to about 200 mg/kg. Desirably, these amounts are provided on a daily basis. However, the dosage to be used in the treatment or prevention of a specific cognitive deficit or other condition may be subjectively determined by the attending physician. The variables involved include the specific cognitive deficit and the size, age and response pattern of the patient. For example, based upon the activity profile and potency of the compounds of this invention, a starting dose of about 10 mg per day with gradual increase in the daily dose to about 200 mg per day may provide the desired dosage level in the human.
Alternatively, the use of sustained delivery devices may be desirable, in order to avoid the necessity for the patient to take medications on a daily basis. xe2x80x9cSustained deliveryxe2x80x9d is defined as delaying the release of an active agent, i.e., a compound of the invention, until after placement in a delivery environment, followed by a sustained release of the agent at a later time. Those of skill in the art know suitable sustained delivery devices. Examples of suitable sustained delivery devices include, e.g., hydrogels (see, e.g., U.S. Pat. Nos. 5,266,325; 4,959,217; and 5,292,515), an osmotic pump, such as described by Alza (U.S. Pat. Nos. 4,295,987 and 5,273,752) or Merck (European Patent No. 314,206), among others; hydrophobic membrane materials, such as ethylenemethacrylate (EMA) and ethylenevinylacetate (EVA); bioresorbable polymer systems (see, e.g., International Patent Publication No. WO 98/44964, Bioxid and Cellomeda; U.S. Pat. Nos. 5,756,127 and 5,854,388); other bioresorbable implant devices have been described as being composed of, for example, polyesters, polyanhydrides, or lactic acid/glycolic acid copolymers (see, e.g., U.S. Pat. No. 5,817,343 (Alkermes Inc.)). For use in such sustained delivery devices, the compounds of the invention may be formulated as described herein.